Texture "stretching"
Have a look at the UV map.
The leaf takes a lot of texture UV space but it's fairly small in 3D space. That way it has a lot of details (=compression).
But the eyes get very little texture space and are big in 3D space. So they have only little texture details (=stretching).
A checkerboard texture can visualize this for you. Ideally, the chess patterns should all be the same size.
You can try to unwrap again with Smart UV Project (What is the difference between Unwrap and Smart uv project?).
Or edit the UV map

scale down the leaf in the UV editor (hover mouse over an UV island and press L to select it).

and try menu: UV → Minimize Stretch. The editor will then try to give the eyes more space (hopefully).